1. Field of the Invention
The invention relates to a direct-current (DC) to direct-current (DC) converter, and more particularly to a DC-DC converter capable of transient response control according to the variation of output voltage of the DC-DC converter.
2. Description of the Related Art
DC-DC converters are widely used in the field of electronics to convert an input DC voltage to an output DC voltage higher or lower than the input DC voltage. Such circuitry or devices, which typically have semiconductor switching-control topology, are highly efficient and small in dimensions, and therefore constitute an important part for power supplies in various electronic apparatuses. A DC-DC converter has a controller, which receives feedback signals, such as current or voltage feedback signals, to adjust the output voltage or current to a desired level.
A DC-DC converter may include a control loop that contains an error amplifier, a pulse-width modulation (PWM) comparator, and one or more drivers, usually coupled with a synchronous rectifier to improve performance. The output voltage is compared with a reference voltage by the error amplifier. The PWM comparator receives the output of the error amplifier as its first input and receives a saw-tooth or a triangle signal as its second input. The PWM comparator's output is a PWM signal that is amplified by the drivers driving the power switches. The advantages of this kind of converters are their simplicity in architecture and high precision. Its major disadvantage, however, is its slow response to load transients because of the compensation needed on the error amplifier. Therefore, a need exists in the art to address the aforementioned deficiencies and inadequacies.